Calculation of solar panels for the home

Calculation of solar panels for the home
Calculation of solar panels for the home

In our modern time, various technologies are actively developing that provide maximum comfort in human activity. In particular, it is worth noting that the development of alternative energy sources is in full swing. A striking example of this is solar panels, which can now be installed on the roof of your own home. And anyone can buy them. This is especially true in cases where the house is located far from power lines. But in order to feel all the benefits and benefits of such a solution, the correct calculation of solar panels is necessary.

General information

The photoelectric effect is a physical phenomenon that was discovered back in 1887 and became the basis for the development of solar panels to generate electricity. Under the influence of light (photons) or any other electromagnetic radiation, the energy of these particles is transferred to the electrons of the substance. In other words, with the help of the sunreceive electricity.

Solar panels on the roof of a private house

After the discovery of this physical phenomenon, it became necessary to control it. For this purpose, photocells were created - special electronic devices of a compact size. They include semiconductor materials.

In industrial production conditions, it has become possible to combine microscopic transducers into massive and efficient panels. Many modern enterprises produce silicon modular designs in large volume. Their efficiency is about 18-22%.

The solar battery includes several similar modules through which photons of sunlight enter the electrical circuit in the form of direct current. Then they enter the storage devices or are converted into an alternating current charge (220 volts). The resulting electrical energy allows household appliances to function.

Features of the calculation of solar panels for the home

This operation comes down, first of all, to determining their power. And for this it is necessary to know what energy load will fall on the entire structure. In other words, how many kilowatts of energy will be consumed monthly.

Solar panels for home

These readings can be determined by observing the electric meter. And if the value is within 100 kW, then the panels should be purchased exactly those that are capable of generating such an amount of energy.

It is also worth considering that the work of solarbatteries in full mode is possible only in daylight. A full issue will be only when the sky is clear. When the angle of incidence of the sun's rays changes, as well as the appearance of clouds on the horizon, the power will decrease by 20%. The same will happen in cloudy weather. All this should not be forgotten.

That is, in the process of calculating solar panels for a private house, you should take the period of time when they work at full capacity. As a rule, this is 7 hours - the period from 9 am to 4 pm. At the same time, in the summer season, the panels can operate from dawn to dusk. But in the past, the percentage of working capacity will be only in the region of 20-30%. During the above hours, you can get the remaining 70%.


As we have already understood, the fundamental factor to consider when calculating solar panels is the energy load. After all, the performance of batteries depends largely on the amount of electricity required to provide a home:

  • Creating a full-fledged station requires the use of powerful panels - from 150 to 250 watts.
  • To maintain the performance of only country lighting, you can get by with low-power batteries - no more than 50 W, which is enough.

How to make such calculations?

Basic Power Consumption

Before calculating the solar battery and battery, it is necessary to determine the total power of all used electric current consumers. To this end, the energy consumption of each unit (appliances, light bulbs, etc.) is multiplied by the number of hours of its use induring the day.

Energy consumption of a private house

After that, add up all the received data. The result is the rate of electricity consumption per day (in kilowatt-hours). This is how much solar panels should produce, and this is the minimum value. Subsequent calculations regarding the number of panels, their cost and other parameters will depend on these data.

However, the whole system is not only composed of solar panels, other components are included here:

  • inverters;
  • batteries;
  • charge controllers.

When calculating the power of solar panels for a home, this should not be discounted either! In batteries, there is a decrease in energy - up to 20%. In this regard, in further calculations, the obtained base value must be increased by this amount.

Electricity consumers

In every home you can find a number of the most necessary appliances. The following technique will always work at certain hours:

  • refrigerator;
  • TV;
  • computer;
  • washing machine;
  • boiler;
  • iron;
  • microwave oven (however, not everyone has one).

There are also other devices, in the absence of which life loses the desired level of comfort. In addition, a certain number of light bulbs, which can reach up to a hundred, light up on the territory of private real estate every day.

Consumers of electricity in a private house

The table below showspower of electrical appliances that are used most often.

Household appliance

Power Rating (W)

Approximate duration of work for one day (hours)

Daily consumption (kWh)








0, 8

Washing machine







1, 5

Light bulbs


About 10





1, 5




0, 5

150 liter boiler

1, 2






0, 1




0, 5

With this table it is convenient to carry out a simplemathematical calculation of solar panels. In this particular example, the daily consumption value is 18.9 kWh. Only this is without taking into account what we usually do not use every day - an electric kettle, a hair dryer, a pump, a food processor, etc. Thus, on average, up to 25 kWh (at least) can be obtained.

The important point is insolation

Before you start counting the number of solar panels, you should take into account such a thing as insolation. Roughly speaking, this term should be understood as the amount of solar energy falling per unit area. This is a very important parameter, without which it is impossible to determine exactly how many panels should be purchased.

After all, even if there is not enough sunlight, no matter how productive the battery is, it will not be able to produce the necessary power. Therefore, you need to understand the importance of this parameter when calculating solar panels. After all, the required level of energy supply will depend on this.

Of course, this parameter is purely individual for each specific region of the country. There are two ways to get this necessary information:

  • specialized directories;
  • electronic meteorological resources.

As you can understand, the maximum value of insolation will fall on the summer period. The minimum values ​​are mainly in the cold months.

Number of batteries

Now you can start counting the number of panels. For this, the found value of the basic consumptionelectric energy per day must be divided by the insolation data of the required month.

Mathematical calculation of solar panels

At the same time, it is important to understand that the calculation must be carried out on a monthly basis, since the data can vary to a different and sometimes significant extent. Now it remains to divide the resulting value as a result of calculating the number of solar panels once again, only by the power parameter of the selected panel. This characteristic is indicated in the passport. If the result is a fractional number, it is rounded up to an integer value and only up. This will be the final result.

Of course, the greater the performance of the panel, the fewer of them will have to be taken. And here everything mainly depends on the size of the family budget and the area of ​​\u200b\u200bthe roof. At the same time, it is necessary to take into account the period of operation of the entire system. Indeed, with a decrease in insolation of solar panels, more will be required than under normal conditions.

Rational spending

Thinking about the calculation of solar panels, it is worth paying attention to illumination. But, as already noted, the number of lamps on the territory of a private house can be large - 100 or more. For this reason, it is worth paying attention to energy-saving light bulbs. As a result, significant savings can be achieved in terms of energy consumption.

In addition, you should purchase household appliances not lower than class A and even A +, A ++, A +++. Ultimately, such a measure will significantly reduce the costs that will be spent on the purchase of solarpanels. In addition, most modern appliances are just designed to consume 12 V.

Energy saving light bulbs

And this is exactly how much photo panels are capable of producing, without the use of additional devices for converting direct current into alternating voltage.

Math example

When calculating the number of solar panels for a house, one should take into account what season of the year the entire system will operate in full mode. And again, everything here is due to insolation. Depending on the month, a different number of photo panels may be required.

For a clearer understanding, it is worth giving a specific example:

  • For example, the daily electricity consumption in the house will be 15 kWh.
  • Insolation parameter - 3 kWh/m2.
  • The power of one panel is 300W or 0.3KW.

Calculate the required number of batteries (denoted by the letter N): N=15/3/0, 3=16, 6. Rounding the resulting value up to an integer, we get the result - 17 panels.

However, in winter, insolation drops significantly and can reach 1 kWh/m2. In this case, you will need significantly more batteries - up to 50.

A number of nuances

On the one hand, the rejection of the dependence of the central power supply implies certain advantages. But there is also the other side of the coin - such a measure is fraught with some nuances that should not be discounted. And first of all, it is necessary to understand that the sun will not shine for all months, without a “break” - after all, the luminaryalso need a "rest".

Calculation of the power of solar panels for the home

For this reason, when calculating solar panels, you should check the archive of weather conditions in the region of residence in order to determine the number of cloudy days. It can be seen that at least 7 days in one month is a period of unfavorable weather. At this time, the solar panels will not be able to provide the required amount of electrical energy.

In addition, you must not forget about the shortening of the day in autumn and spring. Accordingly, the number of cloudy days increases. In this regard, to receive solar energy from March to October, it is necessary to increase the array of panels up to 50%, depending on the region of residence.

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